package basic;

import java.util.Scanner;

public class Xunhuan {
	public static void main(String[] args) {
	double s;
		int i;
		Scanner in=new Scanner(System.in);
		s=0;
		i=1;
		while(i<=100){
			s=s+i;
			i++;}
			System.out.println(s);

		
			
		
		
	}
}
